package org.apache.flink.runtime.dispatcher;

import org.apache.flink.api.common.time.Time;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.runtime.blob.TransientBlobService;
import org.apache.flink.runtime.leaderelection.LeaderElectionService;
import org.apache.flink.runtime.resourcemanager.ResourceManagerGateway;
import org.apache.flink.runtime.rest.RestServerEndpointConfiguration;
import org.apache.flink.runtime.rest.handler.RestHandlerConfiguration;
import org.apache.flink.runtime.rest.handler.RestHandlerSpecification;
import org.apache.flink.runtime.rest.handler.job.JobSubmitHandler;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.handler.legacy.metrics.MetricFetcher;
import org.apache.flink.runtime.rpc.FatalErrorHandler;
import org.apache.flink.runtime.webmonitor.WebMonitorEndpoint;
import org.apache.flink.runtime.webmonitor.WebMonitorExtension;
import org.apache.flink.runtime.webmonitor.WebMonitorUtils;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.util.FlinkException;

import org.apache.flink.shaded.netty4.io.netty.channel.ChannelInboundHandler;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ScheduledExecutorService;

/**
 * REST endpoint for the {@link Dispatcher} component.
 */
public class DispatcherRestEndpoint extends WebMonitorEndpoint<DispatcherGateway> {

	private WebMonitorExtension webSubmissionExtension;

	public DispatcherRestEndpoint(RestServerEndpointConfiguration endpointConfiguration, GatewayRetriever<DispatcherGateway> leaderRetriever,
		Configuration clusterConfiguration, RestHandlerConfiguration restConfiguration,
		GatewayRetriever<ResourceManagerGateway> resourceManagerRetriever, TransientBlobService transientBlobService,
		ScheduledExecutorService executor, MetricFetcher metricFetcher, LeaderElectionService leaderElectionService,
		ExecutionGraphCache executionGraphCache, FatalErrorHandler fatalErrorHandler) throws IOException {

		 // 1、leaderElectionService = ZooKeeperLeaderElectionService
		 // 2、executionGraphCache = DefaultExecutionGraphCache
		super(endpointConfiguration, leaderRetriever, clusterConfiguration, restConfiguration, resourceManagerRetriever, transientBlobService,
			executor, metricFetcher, leaderElectionService, executionGraphCache, fatalErrorHandler);

		webSubmissionExtension = WebMonitorExtension.empty();
	}

	@Override
	protected List<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> initializeHandlers(final CompletableFuture<String> localAddressFuture) {

		// 父类中，初始化超级多一大堆 处理器
		// DispatcherRestEndpoint  extends WebMonitorEndpoint
		List<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> handlers = super.initializeHandlers(localAddressFuture);

		// Add the Dispatcher specific handlers

		final Time timeout = restConfiguration.getTimeout();

		// JobSubmit Handler 任务提交处理器
		// 将来客户端提交应用程序上来，由 JobManager 中的 Netty 服务端的 JobSubmitHandler 来执行处理
		JobSubmitHandler jobSubmitHandler = new JobSubmitHandler(leaderRetriever, timeout, responseHeaders, executor, clusterConfiguration);

		handlers.add(Tuple2.of(jobSubmitHandler.getMessageHeaders(), jobSubmitHandler));

		return handlers;
	}

	@Override
	protected Collection<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> initializeWebSubmissionHandlers(
		CompletableFuture<String> localAddressFuture) {
		if(restConfiguration.isWebSubmitEnabled()) {
			try {
				final Time timeout = restConfiguration.getTimeout();

				//  加载得到： WebSubmissionExtension
				webSubmissionExtension = WebMonitorUtils
					.loadWebSubmissionExtension(leaderRetriever, timeout, responseHeaders, localAddressFuture, uploadDir, executor,
						clusterConfiguration);

				return webSubmissionExtension.getHandlers();
			} catch(FlinkException e) {
				if(log.isDebugEnabled()) {
					log.debug("Failed to load web based job submission extension.", e);
				} else {
					log.info("Failed to load web based job submission extension. " + "Probable reason: flink-runtime-web is not in the classpath.");
				}
			}
		} else {
			log.info("Web-based job submission is not enabled.");
		}

		return Collections.emptyList();
	}

	@Override
	protected CompletableFuture<Void> shutDownInternal() {
		final CompletableFuture<Void> shutdownFuture = super.shutDownInternal();

		final CompletableFuture<Void> shutdownResultFuture = new CompletableFuture<>();

		shutdownFuture.whenComplete((Void ignored, Throwable throwable) -> {
			webSubmissionExtension.closeAsync().whenComplete((Void innerIgnored, Throwable innerThrowable) -> {
				if(innerThrowable != null) {
					shutdownResultFuture.completeExceptionally(ExceptionUtils.firstOrSuppressed(innerThrowable, throwable));
				} else if(throwable != null) {
					shutdownResultFuture.completeExceptionally(throwable);
				} else {
					shutdownResultFuture.complete(null);
				}
			});
		});

		return shutdownResultFuture;
	}
}
